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Posted: 12/26/2023 6:33:56 PM EDT
[Last Edit: spyderboy03]
[#1]
Quote HistoryOriginally Posted By airgunner: @waddlingweezol The gas port on mine is .057" but it will only run suppressed. Unsuppressed it will not cycle (even with a standard 3oz buffer) which Sionics fully warns about with this barrel. If I had to guess, if you want to run suppressed and unsuppressed you would probably need to be in the low .060's range (like ~.063 maybe)? Quote HistoryOriginally Posted By airgunner: Originally Posted By waddlingweezol: Did you ever get a measurement on the gas port size? I saw you said smaller than 0.060, but wanted to see if you knew the exact size. I have a 12.5 ERGP barrel waiting to be built up, but my smallest pin gauge was 0.073 which obviously was too small. I'll probably make this one a dedicated suppressed set up with my DA Sierra 5 since that can was crazy gassy. I wonder what the gas port size is on the 12.5 standard gas port barrel. The gas port on mine is .057" but it will only run suppressed. Unsuppressed it will not cycle (even with a standard 3oz buffer) which Sionics fully warns about with this barrel. If I had to guess, if you want to run suppressed and unsuppressed you would probably need to be in the low .060's range (like ~.063 maybe)? I'm running a .0615 gas port equivalent BRT tube on my 12.5" Geissele barrel. The whole upper is Geissele and it's got a Super 42 w/H2 buffer. It runs great suppressed (a touch gassy, Turbo K), and still runs unsuppressed with my 5.56 reloads (tested down to low 30's for temps). ETA: I did not have to reduce buffer weight when testing unsuppressed as I mentioned probably having to do earlier in this thread. |
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ID, USA
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Posted: 1/7/2024 12:35:56 AM EDT
[Last Edit: Freedom_Lover]
[#2]
Quote HistoryOriginally Posted By acrocat: I love my 12.5. I have a Colt M4A1 upper cut down to 12.5". @acrocat Do you have any pictures of this? I'm considering the same thing and am interested in seeing how the m203 step works out with the 12.5 muzzle. Thanks |
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Posted: 1/7/2024 11:16:08 PM EDT
[#3]
Quote HistoryOriginally Posted By Freedom_Lover: Do you have any pictures of this? I'm considering the same thing and am interested in seeing how the m203 step works out with the 12.5 muzzle. Thanks Quote HistoryOriginally Posted By Freedom_Lover: Originally Posted By acrocat: I love my 12.5. I have a Colt M4A1 upper cut down to 12.5". Do you have any pictures of this? I'm considering the same thing and am interested in seeing how the m203 step works out with the 12.5 muzzle. Thanks Just because I am currently researching/considering the same at the moment:  Attached File Attached File |
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ID, USA
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Posted: 1/8/2024 5:59:10 AM EDT
[#4]
Thank you. What's the lower barrel? It doesn't seem to have the same step cut.
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Posted: 1/8/2024 6:25:37 AM EDT
[#5]
Quote HistoryOriginally Posted By Freedom_Lover: Thank you. What's the lower barrel? It doesn't seem to have the same step cut. It wasn't mentioned by the OP. Definitely not a proper M4 barrel profile. I know that Rosco and few others offer an "M4" barrel in that profile, correct or not. |
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USA
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Posted: 1/9/2024 3:53:51 PM EDT
[Last Edit: acrocat]
[#6]
Quote HistoryOriginally Posted By Freedom_Lover: @acrocat Do you have any pictures of this? I'm considering the same thing and am interested in seeing how the m203 step works out with the 12.5 muzzle. Thanks I can post a picture if needed but the top picture that @TGWLDR posted is pretty much how the step looks. It should work great with a 9" M203 if that is what you are thinking. People have posted pictures of 9" M203 classic receivers with 12.5" barrels here before so it definitely works. FWIW, I went with a .068 gas port and my barrel is a Colt Socom profile barrel. |
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Posted: 1/26/2024 12:51:13 PM EDT
[#7]
Start wearing eye protection, which you should be doing anyway with a suppressor, and you won't even notice the gas. Once you're not worried about the gas, build whatever you want.
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Posted: 1/26/2024 5:26:55 PM EDT
[#8]
Quote HistoryOriginally Posted By Vapor_Man: Start wearing eye protection, which you should be doing anyway with a suppressor, and you won't even notice the gas. Once you're not worried about the gas, build whatever you want. LOL - sorry but that's not how that works. Have you ever shot a suppressed gun? I have a hard time believing you have based on that comment  |
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NC, USA
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Posted: 1/29/2024 10:20:26 AM EDT
[#9]
How about a PWS 11.85" piston upper in .223 Wylde? A substantial improvement to the GTF concern. They're pretty smooth.
Keith |
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IA, USA
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Posted: 1/29/2024 11:56:59 AM EDT
[#10]
My 12.5 Gordy and 14.5 Toob build share an SBR lower and can. The 14.5 is slightly more pleasant but it’s a pretty minimal difference. Both sound great with AEM5/Ops cans. My vote would be 12.5.
 
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Posted: 2/1/2024 12:17:54 AM EDT
[#11]
Quote HistoryOriginally Posted By airgunner: @waddlingweezol The gas port on mine is .057" but it will only run suppressed. Unsuppressed it will not cycle (even with a standard 3oz buffer) which Sionics fully warns about with this barrel. If I had to guess, if you want to run suppressed and unsuppressed you would probably need to be in the low .060's range (like ~.063 maybe)? @Joedirt199 - Do you only run suppressed? Based on my experience with mine, I can't see yours running unsupressed regardless of buffer? Quote HistoryOriginally Posted By airgunner: Originally Posted By waddlingweezol: Did you ever get a measurement on the gas port size? I saw you said smaller than 0.060, but wanted to see if you knew the exact size. I have a 12.5 ERGP barrel waiting to be built up, but my smallest pin gauge was 0.073 which obviously was too small. I'll probably make this one a dedicated suppressed set up with my DA Sierra 5 since that can was crazy gassy. I wonder what the gas port size is on the 12.5 standard gas port barrel. The gas port on mine is .057" but it will only run suppressed. Unsuppressed it will not cycle (even with a standard 3oz buffer) which Sionics fully warns about with this barrel. If I had to guess, if you want to run suppressed and unsuppressed you would probably need to be in the low .060's range (like ~.063 maybe)? Originally Posted By Joedirt199: I cut down a 14.5" midlength gas BCM barrel to 12.5" and run a Turbo3 direct mounted. I also choke down the gas by using vented set screws in all my gasblocks and front sight bases. The vented set screws come with a .049 vent hole but this one is opened to .055. I then tune the buffer and spring for lock back. Some have H buffers and some have buffers with an aluminum weight replaced for a steel weight. They shoot smooth and have next to no gas in your face. Sionics wouldn't tell me their ERGP size. Triarc Systems Suppressed only barrels are .052" - .055" from what I've seen. Sionics looks close. I also see they have a suppressed only option on their product page. The ERGP option as .057" looks good. |
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